The present invention relates to the field of bio-methane production by anaerobic digestion of organic material and more specifically, it relates to an apparatus and system for the production of bio-methane from organic substances contained in animal or vegetable waste.
The management of nutrients contained in animal waste (manure) and vegetable waste is a continuing concern for managers of livestock operations. If mishandled, such wastes can contaminate water supplies with nitrogen and phosphorous salts and organics and microorganisms. One method to control potential contamination is by anaerobic digestion. Anaerobic digestion of organic material, such as animal and agricultural waste is the fermentation of such material by bacteria in the absence of oxygen. However, while various anaerobic digestion processes such as plug-flow and lagoon designs are being practiced, there remains a need for an improved anaerobic digestion that is more efficient and cost-effective then those currently practiced.
A first aspect of the present invention is an anaerobic digester for digesting a slurry of organic waste comprising: a tank having a vertical outer side wall and a vertical lower inner wall, the outer wall and inner wall each having a top surface, a first radiant heating floor between the outer wall and a first side of the inner wall forming a first chamber and a second radiant heating floor between the outer wall and a second and opposite side of the inner wall forming a second chamber, the first radiant heating floor maintaining the slurry in the first chamber at a first temperature and the second radiant heating floor maintaining the slurry in the second chamber at a second temperature; an inlet pipe for delivering the slurry to a lower portion of the first chamber and a outlet pipe for removing digested slurry from a lower portion of the second chamber, the slurry maintained at a depth that is greater than a height of the inner wall; and a gas collection chamber sealed to the tank along the length of the upper surface of the outer wall.
A second aspect of the present invention is a method for digesting a slurry of organic waste comprising: providing a tank having a vertical outer side wall and a vertical lower inner wall, the outer wall and inner wall each having a top surface, a first radiant heating floor between the outer wall and a first side of the inner wall forming a first chamber and a second radiant heating floor between the outer wall and a second and opposite side of the inner wall forming a second chamber, the first radiant heating floor maintaining the slurry in the first chamber at a first temperature and the second radiant heating floor maintaining the slurry in the second chamber at a second temperature; delivering the slurry to an inlet pipe extending into a lower portion of the first chamber; delivering the slurry to an inlet pipe extending into a lower portion of said first chamber; removing digested slurry through an outlet pipe extending into a lower portion of the second chamber; and collecting biogas in a gas collection chamber sealed to the tank along the length of the upper surface of the outer wall.
A third aspect of the present invention is a system for digesting a slurry of organic waste comprising: (a) a preheat tank for preheating the slurry before introducing the slurry to a digester; (b) the digester comprising: a tank having a vertical outer side wall and a vertical lower inner wall, the outer wall and inner wall each having a top surface, a first radiant heating floor between the outer wall and a first side of the inner wall forming a first chamber and a second radiant heating floor between the outer wall and a second and opposite side of the inner wall forming a second chamber, the first radiant heating floor maintaining the slurry in the first chamber at a first temperature and the second radiant heating floor maintaining the slurry in the second chamber at a second temperature; an inlet pipe for delivering the slurry to a lower portion of the first chamber and a outlet pipe for removing digested slurry from a lower portion of the second chamber, the slurry maintained at a depth that is greater than a height of the inner wall; and a gas collection chamber for collecting gas, the gas collection chamber sealed to the tank along the length of the upper surface of the outer wall; (c) an engine coupled to a generator, the engine generating heat by burning the gas collected in the gas collection chamber and driving the generator in order to generate electricity; and (d) a heat exchanger for taking the heat generated by the engine, heating a fluid with the heat and supplying the heated fluid to the preheat tank and the first and second radiant floors.